Lamp base and terminal structure



April 18, 1967 A. M. KRUPP ETAL LAMP BASE AND TERMINAL STRUCTURE Filed Aug. 9, 1965 ..D| UQ sw m m r v OKS 0 NM 1% nm A v owmw m mnc M A b United States Patent 3,315,216 LAMP BASE AND TERMINAL STRUCTURE Anton M. Krupp, Gates Mills, and Melvin L. Stone, Cleveland Heights, Ohio, assignors to General Electric Company, a corporation of New York Filed Aug. 9, 1965, Set. No. 478,207 4 Claims. (Cl. 339-145) The present invention relates generally to electric lamps or similar devices comprising a sealed envelope of vitreous material containing electrical energy translation means such as a filament or electrodes. More particularly, the invention relates to base and terminal structures for such devices especially for devices of the single ended type having a base at one end for supporting the device in a socket and conducting current thereto.

Electric lamps in which the envelope is formed at one or both ends with an external pinch seal of I-shape in cross section through which lead-in conductors extend are now known in the art. The base and terminal structure of the lamps is afiixed to the outer end portion of the external I-shape pinch seal.

The principal object of the present invention is to provide a base and terminal structure for such devices of the single ended type which is of low cost, high strength and readily assembled on and cemented in fixed predetermined position to the I-sh-ape external pinch seal of the envelope. Additional objects and advantages of theinvention will appear from the following detailed description, the accompanying drawing and the appended claims.

The base and terminal structure of the present invention comprises a generally cylindrical ceramic insulator and a cup-like cylindrical metal shell which, when assembled on the Lshape pinch seal as described below fit together on the outer end portion of the seal and form an enclosure confining the basing cement to the interior of the base. The cup-like shell has in its end wall an I-shape slot which makes a snug fit with the I-shape seal. The cylindrical side wall of the shell closely surrounds the end portion of the seal, having an inner diameter closely approaching the width of the I-shape seal. The ceramic insulator has a diametral slot at one end providing a seat for the seal. The slotted end of the insulator fits into the open end portion of the shell. The insulator has also IELH external annular flange providing a seat for the rim of the shell. With the shell and the insulator brought into engagement with the pinch seal and with each other the base is properly aligned with the envelope of the lam! The insulator has an outwardly extending hollow stem which is of reduced diameter and tapers at its outer end. The contact terminals of the base include a threaded metal shell contact afiixed to the cylindrical part of the stem and a metal eyelet contact afiixed to the smaller diameter end of the tapered portion of the stem. The wall of the stem is provided with lead-in accommodating openings at the contacts.

'Ilhe basing cement fills the interior of the shell and extends into the part of the insulator stem adjacent the slotted end of the insulator to fill the slot and close the openings in the stern provided for the shell contact. The base thus is firmly affixed in proper aligned position on the envelope of the lamp.

The outer surface of the cup-like shell is of high reflectance to direct radiant energy away from the base to protect the part of the seal enclosed by the base from excessive temperatures during operation of the lamp.

In the drawing accompanying and forming part of this specification: I

FIG. 1 is a perspective View of an electric lamp bulb with the base of the present invention afiixed thereto;

3,315,216 Patented Apr. 18, 1967 FIG. 2 is an exploded view on an enlarged scale of the base shown in FIG. 1; and

FIG. 3 is a longitudinal section taken along the line 3-3 of FIG. 1 of the base shown in FIGS. 1 and 2 mounted on the outer end portion of the I-sha-ped seal of the lamp shown in FIG. 1, the outer end portion of the seal being shown in side elevation.

Referring to FIG. 1 of the drawing, the lamp illustrated comprises a sealed tubular envelope '1 of light transmitting vitreous material, such as fused quartz or glass. The lamp envelope contains an electric energy translation means in the form of an incandescible filament (not shown) electrically connected across a pair of leadin conductors 2 and 3 (FIG. 3) extending through the I-shaped external pinch seal 4 formed at one end of the envelope 1. Each of the conductors includes a molybdenum foil portion 5 hermetically sealed into the pinch seal and a pair of metal wires 6 and 7 welded to opposite ends of the foil. The wires 6 consist of tungsten and the wires 7 consist of molybdenum at their inner ends and nickel at their outer ends.

In lamps of this type the I-shape pinch seal 4' is accunately formed to predetermined dimensions and in predetermined position with respect to the: incandescible filament mounted in the tubular portion 8 of the envelope to adapt the lamp for precision mounting in optical systems. In accordance with the present invention, the base 9 shown in the drawing is adapted for precision mounting on the pinch seal 4 of the lamp.

To this end the lamp base 9 comprises a cup-like cylindrical metal shell lil and a cylindrical ceramic insulator 11 carrying a metal eyelet contact 12 and a threaded metal shell contact 13 to which the outer ends of the wires 7 of the conductors 3 and 2 are electrically connected, respectively. The shell 10 and the insulator 11 are adapted to fit together and to seat against longitudinally spaced apart portions of the pinch seal 4 when assembled on the seal as shown in FIGS. 1 and 3 to facilitate accurate positioning of the base with respect to the incandescent filament mounted in the tubular part 8 of the lamp envelope 1. When the assembled shell and insulator are filled with basing cement as described below and the cement is cured the base is afiixed to the lamp envelope in proper position.

The cup-like shell 10 is formed from sheet metal and has in its end wall 14 an I-shaped slot 15 which fits snugly the portion of the I-shape pinch seal 4 around the foils 5, as shown in FIG. 3. The inner diameter of the cylindrical wall 16 of the shell 10 closely approaches the width of the pinch seal.

The insulator 11 consists of a molded ceramic electrically insulating material, such as steatite, porcelain, or a high alumina ceramic, and is of hollow, generally cylindrical shape having at one end a diametral slot 17 accommodating the end of the seal 4. The length of the slot 17 is equal approximately to the width of the seal. Two dished seats 18 are provided at the ends of the slot 17 for the outer ends of the flanges 19 of the pinch seal 4. The sides of the slot 17 overlap the outer end portion of the seal 4 and the part of the insulator carrying the slot makes a clearance fit with the rim portion of the shell 10 to define an enclosure around the outer end portion of the seal 4. The insulator is provided with an external annular flange '20 which is engaged by the rim 21 of the shell '10.

The insulator has a hollow stem 22 which tapers at its outer end as shown at 23. The slot 17 of the insulator is open to the interior of the stem 22. The stem is substantially smaller in diameter than the flange 20 and the flange tapers toward the stem to provide a shoulder 24 which may be used to seat the based lamp properly in a socket.

The shell contact 13 is affixed to the cylindrical part of the stem 22 with the rim of the skirt 25 of the shell contact butting against the shoulder 24. The part of the stern engaged by the skirt 25 is slightly larger in diameter than the part thereof engaged by the threads 26 of the contact 13. Two diametrically spaced openings 27 into the interior of the stem are provided in the portion thereof surrounded by the skirt 25 of the contact 13 and corresponding portions of the skirt are bent into the openings as shown in FIG. 3 to aflix the shell contact onto the insulator. A shoulder 28 for seating the radially extending annular flange 29 of the contact 13 is provided between the cylindrical part of the stem and its tapered end 23 as shown in FIG. 3. The eyelet contact 12 is crimped into the opening 30 in the tapered end 23 of the stem.

The base is readily assembled on and atlixed to the pin-ch seal of the lamp in the proper position as shown in FIGS. 1 and 3 by pushing the shell 10 slotted end foremost onto the seal 4 and then filling the space between the shell and the seal with basing cement. The insulator 11 with the contacts 12 and 13 afiixed thereto and with the wires 7 extending through the slot 17 and the opening 30 and one of the openings 27 of the stem is then brought into engagement with the outer end of the pinch seal with the ends of flanges 19 seated in the dished portions 18 at the ends of the slot 17. The insulator is held in position against the end of the seal 4 as the rim 21 of the shell 10 is brought into engagement with the insulator flange 20.

As the shell 10 is moved into engagement with the insulator 11 the cement in the shell is forced, in part, through the bottom of the slot 17 which is wider than the web 31 of the I-shape seal 4. The amount of basing cement forced through the opening between the bottom of the slot and the web of the seal is sufficient to fill the part of the insulator having openings 27 so as to close the openings. The amount of basing cement placed within the shell 10 around the seal 4 is predetermined so as to fill the available space around the enclosed part of the seal as well as the space penetrated by the openings 27 as shown at 32 in FIG. 3. When desired, the part of the insulator 11 defining slot 17 may be lengthened to extend further into shell 10, along the seal 4 and into engagement with the end Wall 14 of the shell 10.

The basing of the lamp is completed by soldering the end of one of the wires 7 to the eyelet contact 12 and the other of said wires to the shell contact 13 by welding and thereafter curing the basing cement in the usual manner.

Hermetic seals 4 of the type shown in FIG. 3 and described above tend to develop leaks when the temperature of the outer ends of the molybdenum foils exceeds the temperature at which molybdenum oxidizes. The outer ends of the foils 5 are exposed to the atmosphere, at least in part, since the wires 7 extending outwardly from the foil do not make a hermetic fused joint with the fused quartz of the seal. Seals of this type are elongated so that the external end portions of the molybdenum foils are spaced a substantial distance from the source of heat within the lamp to avoid oxidation of the foils. To further protect this portion of the seal from the development of temperatures during operation of the lamp which would cause the molybdenum foils to oxidize and the seal to leak the outer surface of the cup-shaped shell 10 is of high reflectance to direct the radiant energy emitted by the lamp away from the part of the seal enclosed by the shell. Accordingly, the cup-shaped shell 10 consists of brass having its outer surface plated with nickel or the shell may consist of aluminum of high reflectance.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A base for attachment by basing cement to the outer end portion of an I-shape external pinch seal of a vitreous envelope of an electric lamp device, said base comprising an insulator and a cup-like cylindrical metal shell for accommodating the said pinch seal portion, said shell having an I-shaped slot at one end for making a snug fit with the seal and a cylindrical side wall having an inner diameter closely approaching the width of the seal, said insulator being of generally cylindrical shape having at one end a diametral slot providing a seat for the seal, the slotted end of the insulator extending into the rim portion of said cup-like shell and defining with said shell a pinch seal and basing cement accommodating space, said insulator having an outwardly extending hollow stern communicating with said slot and being of reduced diameter and tapering at its outer end, said base comprising also a threaded metal shell contact afiixed to said stem adjacent the slotted end of the insulator and a metal eyelet contact atfixed to the smaller diameter end of the tapered portion of the stem, the wall of said stem having lead-in wire accommodating openings at said contacts.

2. A base according to claim 1 wherein the outer surface of the cup-like shell is of high reflectance.

3. A base according to claim 1 wherein the cup-like shell consists of nickel coated brass.

4. A base according to claim 1 wherein the cup-like shell consists of aluminum.

References Cited by the Examiner UNITED STATES PATENTS 2,769,156 10/1956 Caplis et al. 339- 3,256,507 6/1966 Ackerman 339144 FOREIGN PATENTS 753,484 7/1956 Great Britain.

References Cited by the Applicant UNITED STATES PATENTS 2,444,278 6/1948 Betts. 3,001,096 9/1961 Mosby. 3,001,097 9/1961 Smialek.

EDWARD C. ALLEN, Primary Examiner.

W. D. MILLER, Assistant Examiner. 

1. A BASE FOR ATTACHMENT BY BASING CEMENT TO THE OUTER END PORTION OF AN I-SHAPE EXTERNAL PINCH SEAL OF A VITREOUS ENVELOPE OF AN ELECTRIC LAMP DEVICE, SAID BASE COMPRISING AN INSULATOR AND A CUP-LIKE CYLINDRICAL METAL SHELL FOR ACCOMMODATING THE SAID PINCH SEAL PORTION, SAID SHELL HAVING AN I-SHAPED SLOT AT ONE END FOR MAKING A SNUG FIT WITH THE SEAL AND A CYLINDRICAL SIDE WALL HAVING AN INNER DIAMETER CLOSELY APPROACHING THE WIDTH OF THE SEAL, SAID INSULATOR BEING OF GENERALLY CYLINDRICAL SHAPE HAVING AT ONE END A DIAMETRAL SLOT PROVIDING A SEAT FOR THE SEAL, THE SLOTTED END OF THE INSULATOR EXTENDING INTO THE RIM PORTION OF SAID CUP-LIKE SHELL AND DEFINING WITH SAID SHELL A PINCH SEAL AND BASING CEMENT ACCOMMODATING SPACE, SAID INSULATOR HAVING AN OUTWARDLY EXTENDING HOLLOW STEM COMMUNICATING WITH SAID SLOT AND BEING OF REDUCED DIAMETER AND TAPERING AT ITS OUTER END, SAID BASE COMPRISING ALSO A THREADED METAL SHELL CONTACT AFFIXED TO SAID STEM ADJACENT THE SLOTTED END OF THE INSULATOR AND A METAL EYELET CONTACT AFFIXED TO THE SMALLER DIAMETER END OF THE TAPERED PORTION OF THE STEM, THE WALL OF SAID STEM HAVING LEAD-IN WIRE ACCOMMODATING OPENINGS AT SAID CONTACTS. 